Self-locking threaded fasteners have in the past been made by means of a two-part adhesive, such as an uncured epoxy resin and a polymerizing agent. Deposits of the uncured resin and curing agent are applied to the threads of the fastener. The deposits become mixed when the fastener is engaged with a mating member, effecting a cure of the resin to provide a thread lock. The resin has also been micro-encapsulated and the microcapsules mixed with the polymerizing agent to provide a slurry which is applied to the threads. U.S. Pat. No. 3,746,068 discusses micro-encapsulation.
Protection films over the deposits protect them until the time when the fastener is actually engaged with a mating threaded member. Each deposit may be coated with polyvinyl alcohol in a water solution to form the protective film. My prior U.S. Pat. Nos. 4,059,136 and 4,081,012 are of interest in this regard. My prior U.S. Pat. No. 4,325,985 discloses an improvement in which the deposits are coated with ultraviolet curable, protective films. Other patents of interest are U.S. Pat. Nos. 3,489,599, 3,746,068 and 3,814,156.
The present invention is a further improvement in which ultraviolet curable material, rather than being applied as a subsequent coating, is mixed with the resin and curing agent prior to the deposit thereof on the threads of the fastener. That portion of the ultraviolet curable material which is near the surface of the deposits is then cured by ultraviolet light to form a protective skin or film.
These and other objects of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying drawings.